The invention relates to a speed control apparatus for a motor vehicle.
Such a control apparatus is already known from DE-OS 2 546 529 (corresponds to U.S. Pat. No. 4,098,367), in which the new demand value is suddenly issued during changes of the running speed. Since the running speed reacts relatively sluggishly, there may occur control fluctuations which extend over several periods after the new demand value is reached. In order to decrease such overshoot, it is known from DE-OS 2 537 415 (corresponds to U.S. Pat. No. 4,094,378) to employ a controller with a PD-characteristic. However, a PD or P-controller causes the controlled speed to become inaccurate after the setting process due to differing loads and variable play in the positioning member linkage. By contrast, if an I-controller is used, one obtains poorer driving comfort.